Device for cutting off knotted ends of tube bags

Abstract

An annular stopper is placed against one end of the bag to prevent it from advancing, the knotted portion of the bag protruding from the stopper is pinched by a plier, both or either of the stopper and the plier is pulled to extend the portion between the peripheral portion of the bag restricted by the plier, and then the extended portion is cut by the blade of a cutter.

What is claimed is: 
     
       1. A device for cutting off the knotted ends of tube bags comprising: an annular stopper against which the peripheral portion of a bag is pressed; pliers having claws provided at a front end portion thereof arranged opposite to the stopper for pinching the knotted end of the bag projecting from the stopper; a pinch-and-retract means which convert the early stage of its retracting movement, caused by the peripheral portion of the bag abutting against the stopper, into the pinching action of the pliers' claws and which, as soon as the pinching action is achieved, convert the remaining stage of its retracting movement into the retracting of the pliers themselves, with the pinching action of the claws maintained; and a cutting blade which is actuated by achievement of the retracting movement of the pliers to cut the extended portion between the peripheral portion of the bag restricted by the stopper and the knotted end of the bag pinched and pulled by the pliers. 
     
     
       2. A device as set forth in claim 1, wherein the annular stopper is formed by a pair of semicircular members and the gap between the pair of semicircular members is adjusted with their centers aligned by turning a threaded rod according to the size of the diameter of the bag, the threaded rod being formed with a clockwise thread and a counterclockwise thread at its ends. 
     
     
       3. A device as set forth in claim 1, wherein the claws of the pliers are disposed opposite to each other so that they can pinch the portion between the bag content and the fastening ring at the knotted end of the bag. 
     
     
       4. A device as set forth in claim 1, wherein the pinch-and-retract means for the pliers is accomplished by a cam mechanism which converts the retracting movement of an air cylinder rod into the opening of the rear portions of the pliers. 
     
     
       5. A device as set forth in claim 1, wherein the cutting blade is a single straight blade which is incorporated into a parallelogram link so that the blade moves parallelly but in the inclined direction to cut the extended portion of the bag. 
     
     
       6. A device as set forth in claim 4, wherein the annular stopper is mounted to be retractable, and there is provided a valve for actuating the air cylinder rod which is operated with the retraction of the stopper when the latter is pressed by the peripheral portion of the bag. 
     
     
       7. An automatic device for continuously cutting knotted ends of bags comprising: a conveyor having a number of carrier plates arranged parallelly at regular intervals mounted thereon, the conveyor repeating the intermittent movement, alternately, of a halt of a certain duration and an advancement of a certain interval; a pair of bag knotted ends cutting units installed on the opposite sides of the conveyor, the both units being directed toward the stop position of the carrier plates on the conveyor and arranged so as to act toward the carrier plate stop positions, the pair of cutting units further comprising a retractable annular stopper blocking the advancement of the peripheral portion of the bag, pliers having claws at a front end portion thereof arranged opposite to the knotted end of the bag so as to pinch the knotted end projecting from the stopper, pinch-and-retract means for the pliers activated with the retraction of the stopper when the latter is pressed by the peripheral portion of the bag, the pinch-and-retract means converting the early stage of its retracting movement into the pinching action of the plier claws and, as soon as the pinching action is achieved, converting its retracting movement into the retracting movement of the pliers themselves with the pinching action maintained; a cutting blade actuated against the force of a spring to cut the extended portion of the bag between the peripheral portion of the bag restricted by the stopper and the knotted end of the bag pinched and pulled by the pliers as the plier is retracted; and a pair of pushers arranged across and on the opposite sides of the conveyor and directed toward each cutting unit, the pair of pushers being adapted to project to push a bag each time the conveyor stops.